606 Introduction to the Study of Science 



296. Antitoxins. Antitoxins are curative and also give 

 passive immunity for a relatively short period. The best 

 known and perhaps the most important are those for diphtheria 

 and tetanus, the tuberculins and many others being still in the 

 experimental stage. Antitoxins are employed also in immuniz- 

 ing animals against certain kinds of infection, such as hog- 

 cholera and influenza in horses. 



Because of the importance of the antitoxins, a brief account 

 of the manufacture of the diphtheria antitoxin, which is typical, 

 is presented to show the exact care and precautions exercised 

 in its preparation. 



An antitoxin serum, as it is seen in the market, is in either 

 dried or liquid form. It is administered in solution hypoder- 

 mically, and as it is absorbed, begins immediately to neutralize 

 the free toxins in the body and to break down any chemical 

 unions of toxin and cells. It is a specific, attacking only that 

 toxin for which it is the antitoxin. 



The preparation of diphtheria antitoxin is begun with a 

 culture taken from a patient, and this culture is developed in 

 a special medium kept at a suitable temperature. The result- 

 ing culture must be freed from any microbes of different kinds. 

 This is done by inoculating with it tested guinea pigs, in which 

 the bacteria of diphtheria may be isolated and secured in per- 

 fect purity. Purity of bacteria is necessary in order to get a 

 specific antitoxin and to avoid danger to life or health by the 

 introduction of harmful microbes. Tests to determine purity 

 are emploj^ed at every step of the process. 



The bacteria of diphtheria obtained from the guinea pigs 

 are now put into a beef broth medium and incubated at a tem- 

 perature of 37. 5 C. for seven to ten days. They develop 

 rapidly and produce their toxic substances. The product is 

 examined with the aid of a microscope to detect any possible 

 contamination. The pure culture is treated with a preservative, 

 such as carbolic acid, and filtered to remove all the bacteria 

 from the toxic fluid or serum. The filtered serum is bottled 



